Ethyl alcohol-induced cardiovascular malformations in the chick embryo.

Chick embryos incubated for 72-80 hours were exposed to various volumes (0.20-0.40 m1/egg) of 50% ethyl alcohol. Examination of embryos at day 14 of incubation showed that higher doses of ethanol decreased the survival rate of embryos compared with control embryos. Three major categories of cardiovascular malformations were observed in this study: intracardiac anomalies characterized primarily by isolated ventricular septal defect, ventricular septal defect with overriding aorta, double outlet right ventricle or common aorticopulmonary trunk; aortic arch anomalies; and subclavian artery anomalies. Frequencies of embryos with intracardiac anomalies were equal to or greater than 64.8% in the six groups exposed to ethanol. Administration of ethanol also induced high frequencies of embryos with subclavian artery anomalies (11.2-89.1%). Absence or hypoplasia of the right and/or left secondary subclavian artery was commonly associated with persistence of the corresponding primary subclavian artery. Bilateral absence and/or hypoplasia of the secondary subclavian arteries was more common than unilateral anomalies, whereas absence of the left secondary subclavian artery was more commonly observed than an absent right secondary subclavian artery. No embryos in the two control groups combined (n = 94) demonstrated aortic arch or subclavian artery anomalies.